In a liquid spray device such as an ink-jet printer, a liquid spray head sprays liquid such as ink onto a medium such as a print sheet. This may cause a phenomenon called cockling in which the sheet swells due to the liquid, and gets a wavy surface with convex parts and concave parts. For example, PTL 1 discloses a configuration in which a platen opposite to a spray surface of the liquid spray head through which the liquid is sprayed is provided with a plurality of ribs arranged at a regular pitch determined with a positional relation between the ribs and a sheet feed roller taken into consideration. A sheet is conveyed by the roller while being supported by the ribs of the platen, whereby the sheet is shaped such that a cockling pattern (pattern formed by the convex parts and the concave parts) can match the pitch of the ribs, thereby suppressing excess cockling of the sheet.